This invention relates to a hollow stabilizer for a vehicle, which is made of a single pipe and has a torsion section coupled to a vehicle frame, curved sections each integrally extending from each end of the torsion section and arm sections each integrally extending from each curved section and having a free end coupled to a wheel suspension.
Stabilizers of this sort have hitherto been used for the purpose of improving the feel of riding and stability of vehicles, such as automobiles, by improving the tilting of the vehicle at the time of turning, caused by centrifugal forces and imbalance of the road holding force on the opposite side wheels. Usually, the stabilizer has a construction constituted by a single metal pipe, which has a central torsion section terminating at the opposite ends in curved sections defining an obtuse angle and terminating in turn in respective arm sections. The torsion section is coupled to the frame of the automobile or the like via mounting members such that it extends in the lateral direction, while the arm sections are coupled to the opposite sides of a vehicle suspension via coupling sections provided at their free ends. Mounted in this way, the stabilizer acts to suppress the outward tilting of the vehicle and also the floating of the inner wheels at the time of the turning of the vehicle.
With this stabilizer the stress distribution is such that the bending stress is mainly produced in the arm sections and curved sections and maximum in a portion of the curved section adjacent to each arm section and that the shearing stress is not produced in the arm sections at all but is uniformly produced in the torsion section, with the maximum stress mostly produced in the curved sections. Thus, the shape of the stabilizer has to correspond to the aforementioned stress distribution and is determined by taking the weight of the vehicle body, the centroid thereof and the construction of the vehicle suspension into consideration.
In order to reduce the weight of the stabilizer it has been in practice to manufacture the stabilizer from metal pipe. In this case, however, if the pipe thickness is excessively reduced for increasing the weight reduction factor the bending rigidity is reduced. Accordingly, it has been proposed to set the outer diameter and thickness of the pipe such that the torsion spring constant thereof is substantially the same as that of a solid material. By so doing, however, the second moment of area is reduced, and the rigidity particularly of the arm section, in which the bending stress is concentrated, is liable to be insufficient. In such a case, in which the bending rigidity of the stabilizer is comparatively low in particular sections, it is necessary to use a pipe of a large thickness to improve the rigidity of the stabilizer as a whole, and this is not considered to be the best measure for the weight reduction.